High speed web forming machine



April 22, 1969 R. E. SMITH HIGH SPEED WEB FORMING MACHINE Sheet FiledOct. 19, 1965 I NVENTOR.

ROBERT E. SMITH TZZOFQQ A T TOR/VE Y.

April 22, 1969 R. E. SMITH HIGH SPEED WEB FORMING MACHINE Filed Oct. 19,1965 INVENTOR.

ROBERT E. SMITH TNQ TNW

ATTORNEY.

United States: Patent O U.S. Cl. 162-351 3 Claims ABSTRACT F THEDISCLOSURE A papermaking machine wherein a stock slurry is delivered toan endless wire at a forming zone, which may be open to atmosphere undervacuum, with the wire and its supported web passing from the formingzone in seriatim over a plurality of low vacuum zones, the wire beingsupported in part by a plurality of grooved iin type capillary rollswhich themselves deline sections of partitions between adjacent vacuumcompartments, the other sections of partitions being formed by wallportions of the compartments, with the'confronting rolls and wallportions being sealed by means of labyrinth seals wherefore a lowfriction resistance is experienced over each of the vacuum areas so asto result in low driving horsepower requirements.

This invention -relates to papermaking and like machines, and moreparticularly to a simplified construction of a high speed web formingmachine for for-ming webs from slurries of iibrons materials underimproved degrees of drainage control and at accelerated rates of speed.

The invention is aimed primarily at avoiding employment of the costlyrotatable drum of the conventional cylinder mould and thereby theattendant heavy expenditure of power in driving same. By dispensingtherewith, the construction of the machine is simplified, particularlyas respects the drum per se and the connections of suction supply to itsinterior.

As a principal feature hereof, I provide improvements in the wet end ofa papermaking machine used in extracting water from pulp conveyed ontoand via an endless wire wherein the said wire is a relatively short oneand yet is capable of forming sheets under varying degrees of vacuum andfurther wherein I provide a controlled drainage rate and hence acontrolled web formation through a plurality of spacedseparately-controlled low-vacuum boxes with the endless wire beingconveyed relative thereto with a minimum amount of friction, thecommonly-used type of suction box being a chief cause of wear andstrain.

Stated in another way, the invention comprehends means, for deliveringstock to a continuously moving endless wire, cooperant with means forguiding the Wire over an extended substantially oval or circular path,and means for applying suction to at least a part or parts of theinterior of that endless path, therewith to remove the liquid from thestock deposited upon the wire.

The invention may be embodied in any device wherein a stock slurry isdelivered to an endless wire at a forming zone, which may be open toatmosphere under vacuum, with the wire and its supported web passingfrom the forming zone in seriatim over a plurality of low vacuum zones,the wires being supported in part by a plurality 0E grooved n typecapillary rolls which themselves define sections of partitions betweenadjacent vacuum compartments, the other sections of partitions beingformed by wall portions of the compartments, with the confronting rollsand wall portions being sealed by means of labyrinth seals wherefore alow friction resistance is experienced 3,440,138 Patented Apr. 22, 1969ice over each of the vacuum areas so as to result in low drivinghorsepower requirements.

Another feature hereof lies in the allowance of the exploitation of lowvacuum sources, such as fans or the like, made possible by reason thatthe objectionable centrifugal forces, inherent with forming devicesemploying drilled shells such as in cylinder moulds or suction breastrolls are not here present, thereby to permit higher machine speeds withlower driving horsepower requirements.

Additionally, the grooved or finned rolls hereof, being in directcontact with and supporting the wire, realize the desirable generationof only low spouting forces with lessened formation disruption as thewire travels relative thereto.

The finned rolls preferentially will be of two types, a high fin rollused in areas where there is a large quantity of fluent material to copewith and a low n roll used in areas where the removal of water is notnecessarily the primary desiderations but where the unique sealingarrangement is nonetheless requisite in serving the function ofcontrolling the pressure drop through the labyrinthian passage delinedby the seal.

Another object of the invention is to provide a labyrinth gland packingbetween a moving part and a iixed part of the machine to provide abarrier to the passage of gas and/ or fluid into certain portions of themachine. Here, one of the two relatively movable elements to be sealedcarries a series of axially spaced annular bales or teeth or grooves orfins forming an annular comb and mounted thereupon or integral therewithand extending toward the other element, the comb being complemental to alinear comb mounted upon or integal with the other relatively movableelement, which linear comb is interdigitated with the first named combto form an effective labyrinth sealing of the interval between the tworelatively rotatable members so as to insure against escape of gas orfluid either while the apparatus is stationary or rotary. That is, onecomb extends toward and into the other one so that the space between theperiphery of an annular seal element (normally on the rotor) and theadjacent complemental surface (normally on the stator) is as small as ispractical. The high pressure gas or uid passing through this space ateach tooth experiences a drop in pressure so that, after passing thesuccessive teeth which constitute the seal, the pressure of the gas orfluid has fallen substantially to the pressure on the low pressure sideof the seal.

As aforesaid, it is advantageous for the space between the free edge ofthe seal element and the adjacent surface to be as small as possible. Inpractice, however, the cornponents of all rotary machines are subject todistortion due to centrifugal forces, temperature variations, andacceleration and gyroscopic forces, all necessitating certain minimumclearances between the teeth of the combs so as to avoid excessiverubbing contact. In the labyrinth seal hereof, the glands may beconstructed of relatively thin material in case weight reduction is akey consideration and, at the same time, I provide a stiff structure towithstand the distroting forces normally encountered in operation and itis a further object to provide a seal including seal elements which,should they come in contact with each other, will distribute the rubbingload over a relatively wide area and will, therefore, reduce thetendency to cause excessive wear at the surfaces.

In many cases, the distortion of one part may close the gap between theparts of the labyrinth seal and cause rubbing of the parts. Thisdifficulty of course might be obviated by increasing the sealclearances, an unsatisfactory solution because the leakage of the sealincreases. The present invention solves this problem by virtue of thenovelty of the labyrinth seal design in that the seal is constituted bya non-rotating part mounted so that it can shift slightly in a planetransverse to the axis of the rotating part so that, if contact due tonon-concentricity occurs the stationary seal part may be shifted tocenter itself and thus prevent the wearing away of the parts by rubbingwhich would otherwise occur and which would cause an increase in sealclearance.

The labyrinth seal portion of the invention is described in terms of itspreferred embodiment in a papermaking machine and the advantages of thispart of the invention will be recited in terms of this environment.

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter which I regard as myinvention, it is believed that the characteristic features novel withthe invention, as to its construction and purpose, will be betterunderstood from a consideration of the following detailed description ofa prefered embodiment forming a part of this specification, when read inconjunction with the accompanying drawings, wherein:

FIG. 1 is a diagrammatical elevational view of a preferred embodiment ofa high speed paper forming section of a papcrmaking machine showing theendless wire belt and the forming and vacuum zones according to thestructure of the invention, with the framework indicated in dot and dashlines;

FIG. 2 is a broken top plan view of the structure shown in FIG. 1 withthe framework shown in solid lines;

FIG. 3 is an enlarged broken side elevational and part sectional view ofa finned roll of the invention in sealing relation to a suction box sidewall; and

FIG. 4 is a fragmentary sectional view of a modified form of finned rollin sealing relation to a suction box side wall.

Referring to the drawings, the machine generally comprises and endlesspaper forming wire band 10, called the wire, which follows an extendedcircuitous path through a main forming zone, generally indicated by 12,in which the stock slurry is delivered, and thence in seriatim through aplurality of vacuum zones, generally indicated by 14 as a primary vacuumzone, by 16 as a secondary vacuum Zone, and by 18 as a tertiary vacuumzone.

Endless wire is of wire mash, composed of fine wires made of metal suchas bronze in the case of the warp wires and possibly brass in the caseof the filler wires, which wire may vary in length, according to themachine size, as from a length of 60 to one of 100 or more, which may beof any width from under 36 to over 300", and which may rotate generallybetween and be cntrained about a plurality of rolls to be defined.

Preferably, the means for guiding wire 10 over the said extendedcircuitous and endless path which comprises a pair of generallyhorizontal runs or reaches of the wire at its upper and lower portionsand an inclined reach or run of the wire leading from the lowermosthorizontal run to the uppermost horizontal run and a declined reach orrun leading from the uppermost horizontal run to the lowermosthorizontal run, comprises a framework or structural member which is, forthe purposes of the present invention, immaterial and may be constitutedby a pair of spaced apart side frames 20, and a plurality of freelyrotatable supporting rollers extending longitudinally between andstrategically spaced around the side frames to more or less definesubstantially the oval shaped path of the wire and to perform thefunction of guiding the endless wire over the said oval shaped extendedcircuitous and endless path.

The wire is of a width slightly less than the spacing between the sideframes and is guided over the rolls around the said path all in mannersuch that the structural member at its top, bottom and opposite ends issubstantially enclosed by the wire which forms an endless perforatewall.

A breast roll 22 and a turning roll 24 are rotatably mounted in andextend between the side frames of the framework, the breast roll beinglocated adjacent the leading end of the machine, and the turning rollbeing located adjacent the discharge end thereof. Said rolls 22 and 24may be mounted on shafts 26 and 28 respectively journalled in the usualanti-friction or ball bearings mounted on bearing blocks, not shown, inthe spaced side frames. A guide roll 30 is rotatably mounted in andextends between the side frames and its shaft 32 may be similarlyjournalled, and a stretch roll 34 is likewise rotatably mounted in andextends between the spaced side of the framework and its shaft 35 may belikewise similarly journalled in anti-friction or ball bearings suitablymounted on bearing blocks.

Means 36 of conventional design may be provided to adjust thepositioning of the stretch roll for adjusting the tensioning of thewire, and additional adjustment means, in the form of cantilever supportbeams 38, may be provided for adjusting the positions of the breast rolland turning roll relative to the wire.

A plurality of grooved fin rolls or capillary rolls, now to bedescribed, are rotatably mounted in and extend between the spaced sideframes of the framework, each roll serving as the rotor of the labyrinthseal sealing between such rotor and a stator, as will be defined.

As shown in FIGS. 2 and 3, each finned roll is a straight-grooved rollof a type of capillary roll having annular straight walled grooves in aplane at right angles to the axis of the drum of the roll. The roll maycomprise a metal core or shaft 42 covered or sleeved with a thicksheathing 44 of rubber or bronze or other resilient material in theouter periphery of which a plurality of longitudinally-spaced annulargrooves 46 `are machined or otherwise formed so as each to be separatedby annular lands or fins 48 allowing an outwardly-facing anti-frictionfacing defined along the circular zone represented by the line X whichlens itself to being lubricated by the water.

On the other hand, the finned covering element may be of a very hardmaterial lubricated by water such as the wood lignum vitae.

The finning on the roll may be otherwise comprised of a number ofannular discs, connected by spacer rings of lower height and mountedupon the outer periphery of core or shaft 42 or may be comprised of asingle unitary ring fixed to the core or shaft as by bolting or the likewith the ring including a cylindrical peripheral portion bearinglabyrinth seal ribs.

If desired, and as graphically represented in FIG. 2, the grooves ineach succeeding roll may not be in alignment with those of the precedingroll but may be staggered, wherefor the grooves in one roll will not bedirectly in front of or behind the grooves in the roll immediatelyadjacent it, but will be offset from it.

The grooved rolls may -rotate in anti-friction bearings which may be ofthe roller or ball bearing type so as to help to land the rolls in thebearings relative the top of the framework.

The turning roll is normally driven by any suitable powe-r means anddrives the wire which in turn rotates the breast roll, the guide roll,stretch roll, and finned rolls, or the various rolls may be otherwiserotated. If desired, the various rolls may be driven by a t-rain ofgears keyed to the respective shafts, and to insure that all the rollsrotate in the same direction, idler gears may be provided between eachof the main gears. The gears may be driven by any suitable arrangement,either from a rotating member on the machine or by a separate motor.

To prevent the respective shafts from twisting by the driving torque,auxiliary bearings (not shown) may be provided on the outside of therespective gears.

The framework is provided with an inlet means at its leading end for thedischarge of stock onto an nclined portion of the wire at the formingzone upwardly of the breast roll and downwardly of a first grooved finroll, to be further defined, so as to introduce the mixtu-re of pulp andwater in a flow tangential to the direction of movement of the wire, asindicated by arrow a, and through a throat or narrow discharge outlet 62leading froma stock supply (not shown).

If desired, a forming board 64, which alternatively may comprise suctionboxes, may be placed in position at the forming zone under the wirewhere no or little water drains from the wire.

The rst or primary grooved fin roll 70 of a trio of high-finned rolls70, 80 and 90, is disposed immediately adjacent and above for-ming board64, with the wire being carried over the top of said primary grooved finroll.

The second grooved fin roll 80 of the trio of high-finned rolls isdisposed on the opposite side of rst roll 70 and in spaced relationshiptherewith.

A water deflector 72 may be disposed between first and secondhigh-finned rolls 70` and 80 respectively.

Forwardly of second roll 80, the third grooved fin roll 90 of the trioof high-finned rolls is disposed.

A water deflector 82 may be disposed between second and thirdhigh-finned rolls 80 and 90 respectively.

Forwardly of third roll 90, a fourth grooved fin roll 100,preferentially of low lin type, is disposed.

A water deflector 92 may be disposed between highfinned roll 90 andlow-finned roll 100 respectively.

First and second rolls 70 and 80 of the trio of highfinned rolls may bedisposed in different horizontal planes with second roll 80 being in aplane above the plane of first roll 70, wherefore the wire is carriedover the tops of said rolls and on an incline through what is defined asthe primary vacuum zone 14.

Second, third and fourth rolls 80, 90 and 100 respectively are disposedin the same horizontal plane coincident with the plane of guide roll 32.

First and second rolls 70 and 80 respectively cooperantly definetherebetween primary vacuum zone 14 below the plane of the wirestretched therebetween and enclosed by a pair of primary vacuum zonewalls 112 and 114 extending tangentially and outwardly from oppositesides of a primary vacuum pipe 116, which Iwalls have outer upper freeplanar edges so configured as to serve as seats for the stators of thelabyrinth seals between the respective of the primary and secondaryrolls. That is, each of said rolls is sealed relative to the respectivewall of the vacuum box by a seat of a labyrinth seal 118 (see FIG. 3),having grooves 120 and lands 122 which mate with the grooves and landsof respective rolls 70 and 80.

The finned rolls and labyrinth seals may be otherwise formed as shown inFIG. 4, wherein a roll having a thick sheathing 344 of rubber or bronzeor other resilient material in the outer periphery of which a pluralityof longitudinally-spaced annular grooves 346 having tapered side wallsare machined or otherwise formed so as each to be separated by annularlands or fins 348 having tapered side walls, and mating withcomplemental grooves 320 and lands 322 provided in a labyrinth seal 318secured to the upper edge of a vacuum zone wall 312.

Such tapering of the walls of the grooves and lands greatly facilitatesmachining operations. Sealing is accomplished by the pressure drop whichoccurs between the roll and the stationary wall.

Primary vacuum pipe 116 is connected to a suitable vacuum source, notshown, and the peripheral surface thereof between walls 112 and 114 isapertured or may be cut away to provide vacuum to the primary vacuumzone interior.

Second and third rolls 80 and 90l cooperantly define therebetweenseconda-ry vacuum zone 16 below the plane of the wire stretchedtherebetween and enclosed by primary vacuum zone wall 114, a secondaryvacuum zone wall 124 fixed to one side of and extending tangentially andoutwardly from one side of a secondary vacuum pipe 126 and Xed at itsouter free end to primary vac-num zone wall 114, and a secondary vacuumzone wall 128 extending tangentially and outwa-rdly from the oppositeside of the pipe 126, to third roll `90. As `with walls 112 and 114,wall 128 has an outer free end edge serving as a seat for the stator ofa labyrinth seal 118 having grooves and lands which mate with thegrooves and lands of third roll 90.

Secondary vacuum pipe 126 is connected to a suitable vacuum source, notshown, and the peripheral surface thereof between walls 114, 122 and 124is apertured or may be cut away, as with primary vacuum pipe 116-.

Third roll 90 and fourth roll 110 cooperantly define tertiary vacuumzone 18 below the plane of the wi-re stretched therebetween and enclosedby secondary vacuum zone wall 128, a tertiary vacuum zone wall 132 fixedto one side of and extending tangentially and outwardly from one side ofa tertiary vacuum pipe 136 and secured to secondary vacuum zone wall 128and a tertiary vacuum zone "wall 134 extending tangentially andoutwardly from the opposite side of pipe 136. As with walls 112, 114 and128, wall 134 has an outer free 'end edge serving as a seat for alabyrinth seal 118 having :grooves and lands which mate with the groovesand lands of fourth roll 100.

Tertiary vacuum pipe 136 is connected to a suitable vacuum source, notshown, and the peripheral surface thereof between walls 128, 132 and 134is apertured or may be cut away, as with pipes 116 and 126.

The finned rolls will be of two types, namely, highfinned or low-finned,with the trio of rolls 70, and preferably being of the high fin typewith the grooves between the lands or `fins thereof preferentially beingin the order of about 1A" in width with the lands being about ls" inwidth and about 1" in depth, and with fourth roll and breast roll 22being of the low fin type with the grooves between the lands or finsthereof preferentially being in the order of about 1A" in width, withthe lands being about Ms" in width and about 1A in depth.

The outer periphery of each roll defines an outer surface which is asurface of revolution and which is coaxial with, parallel to and closelyspaced from the outer surface of revolution of a wall of a vacuum zonesupported by the structural member.

If desired, means may be provided for manually moving the non-rotatingmember of the seal so as to shift same slightly in a plane transverse tothe axis of the rotating part so that, if contact due tonon-concentricity occurs, the stationary seal part may be shifted tocenter itself and thus prevent the wearing away of the parts by rubbingwhich would otherwise occur and which would cause an increase in sealclearance.

To prevent end leakage between the respective rolls and the forming Zoneand/ or the various vacuum zones, there may be provided at the free endof the rolls and each adjacent side frame a seal in the form of apacking gland, not shown, which is held in situ by any suitable means.

The openings under the two side edges of the endless wire above the topof the forming zone and between the rolls may be closed with sealingstrips, not shown, which may be made of or covered with resilientmaterial such as rubber.

Because the rolls have straight grooves at their ends under the edges ofthe endless belt, the sealing strips can be made to t into and acrossthe outermost groove of each finned roll and thus make a continuous endseal between the rolls, the top of the forrning zone and the under edgeof the wire.

Since the surfaces in the annular grooves are in a plane at right anglesto the axes of these rolls, these surfaces give excellent support to theend sealing strips at each end of the forming zone against atmosphericpressure when there is a partial vacuum in that portion of the endlessbelt immediately above the top of the forming zone.

The stock formed on the wire is a thin continuous layer as it passesover the forming zone and the successive low vacuum zones, and isremoved from the wire as by any of the conventional devices such as apickup couch roll 250 having a pickup felt 252 entrained therearound.

The main forming zone may be open to the atmosphere, or be under vacuum.

The stock on the wire passes from the forming zone over the plurality ofvacuum zones, with the endless wire being supported by the groovedfin-type rolls which also provide rotating partitions between the'vacuum compartments.

The vacuum compartments are sealed by the labyrinth seals which matewith the grooves and lands of the iin rolls.

The vacuum compartments may also be equipped with water deflectors, asshown.

Low vacuum sources are permitted because the objectionable centrifugalforces inherent with forming devices which employ a drilled shell, suchas a suction breast roll or a Rotoformer, are not set up within themachine.

The machine is mounted upon the pair of spaced cantilever support beams38 whereby the entire machine may be cantilevered, facilitating wirechanging. That is, the wire may be changed by cantilevering the entiremachine and slipping the wire into position. The slack necessary forchanging the wire may be obtained by adjusting the positioning of thestretch roll.

A vacuum source and exit in the form of a fan or the like, not shown, isprovided in each vacuum pipe 116, 126` and 136.

Main forming compartment 12, provided rearwardly or inwardly of formingboard 64, is bounded along its upper side by finned roll 70, vacuum zonewalls 112 and 124 and by vacuum pipes 116 and 1216, and is bounded atits inner or rearward end by an upright wall 260 sealed at its upper endto -vacuum pipe 126. Forming compartment 12 is bounded along its lowerside by an upwardly curved extension 262 of wall 260, by one of saidcantilever support beams 38, and by breast roll 22.

Any suitable vacuum or exhaust means may be provided in a dischargeorifice 264 of the forming compartment, or the compartment may be venteddirectly to atmosphere.

In operation, stock in the form of a brous slurry is delivered to thewire at forming board 64 where the stock is optionally subjected tovacuum at main forming compartment 12 to remove water therefrom. As thewire continues in its travel, it delivers the stock to the series ofadjacent low vacuum zones 14, 16 and 18 defined by the spaced fin-typerolls, each such vacuum zone allowing the extraction of water from theweb. From the last vacuum area 18, the formed web is delivered by thewire to pickup felt 252 running with pickup couch roll 250.

Herein, web formation is controlled by the use of low vacuum, same beingimportant for porosity control and sheet formation. The low frictionresistance over the vacuum areas, due to the labyrinth means between thefinned rolls and the stationary zones, results in low driving horsepowerrequirements; the grooved rolls are in contact with and support thewire, resulting in low spouting forces with resultant lessened formationdisruption.

A controlled drainage rate is permitted for controlled formation, due tothe plurality of vacuum zones separately controlled, and the entiremachine design permits the use of economical short wires which are easyto change because of the cantilever-type machine mounting.

Water in the stock is filtered through the wire mesh leaving the wetfibers on the upper planar surface of the wire, and the drainage wateror white water is pumped back into circulation from the catch basins,not shown. The fibers deposited on the wire form a fiber web or sheet ofa desired thickness which is taken off the wire by pickup couch roll 250and transferred to pickup felt 252.

Secured in the side frames and connected to vacuum pipes 116, 126 and136 are conduits, not shown, adapted to be connected to a source ofvacuum for removing drainage or white water from the respective vacuumzone to recirculate-it to the stock supply. Any other suitableconnection may be made to the side frames for drainage of the whitewater, it being realized that since the side frames are stationary, theconnection of vacuum and drainage pipes to the interior of the vacuumcompartments is greatly simplified as compared with correspondingconnections to a rotating wire-covered drum in previous constructions.That is, in vie'w of the fact that the framework is stationary, withonly the wire forming the periphery of the framework and the rollsrotating, it is possible, in simple Imanner, to apply suction to theunder surface of the wire as it passes over the framework, because thepipes for supplying the suction do not have to pass through rotatingparts with the consequent necessity of providing expansive seals forsuch connections.

It should be understood that further modifications may occur to thoseskilled in the art without departing from the spirit and scope of myinvention, and that my invention is not limited to specific details ofconstruction and arrangement thereof herein illustrated.

What I claim and desire to secure by Letters Patent of the United Statesis:

1. A high-speed web-forming machine for processing a fibrous stockslurry comprising, a travelling endless wire meshfa plurality of lowvacuum compartments disposed below said endless wire mesh, partitionsbetween adjacent vacuum compartments, a plurality of rotatable groovedtin-type rolls supporting the Wire mesh, the rolls forming uppersections of the partitions and the wall portions of the compartmentsforming lower sections of the partitions, and labyrinth seals forsealing the confronting rolls and wall portions, wherefore a lowfriction resistance is experienced over each of the vacuum areas so asto result in low driving horsepower requirements.

2. A high-speed web-forming machine as set forth in claim 1, including arotatable grooved fin-type breast roll in running relationship with theendless wire mesh.

3. A high-speed web-forming machine as set forth in claim 2 wherein thegroove formation in the breast roll and in certain of the fin-type rollsdiffers from the groove formation in others of the fin-type rolls.

References Cited UNITED STATES PATENTS 2/1926 Jones 162-373 2/1953Campbell 162-373 U.S. Cl. X.R.

